Extinguishing Class D fires, that is combustible metal fires, is exceptionally difficult. There were no known liquid firefighting agents prior to the invention in the parent applications which were capable of extinguishing Class D fires. While the compositions shown in the parent applications worked very well in extinguishing Class D fires, under some circumstances they are as easy to apply with conventional firefighting equipment (e.g. nozzles and the like) as is desired. However according to the present invention, a liquid formulation for Class D firefighting is provided which is essentially as effective as the compositions in the parent applications, yet can be readily applied with conventional firefighting equipment. The liquid formulation according to the invention includes a linear alkylbenzene sulfonate, non-ionic detergent and lauric superamide detergent mixture comprising the majority of the total mass of the formulation. Sodium chloride is provided in an amount of about 4.5-41%, preferably about 4.5-12%. While vitamin B-6 and bicarbonate of soda can be provided in the amount up to about 3 and 18% respectively, preferably no vitamin B-6 or bicarbonate of soda is provided. 0 to 4% by weight of the detergent mixture may be coloring and perfuming agents, and a volume of water is provided only large enough to provide effective mixing of the other components of the formulation, but insufficiently large to interfere with the use of the formulation as an effective Class D firefighting agent. The detergent mixture component of the formulation preferably comprises, by volume: about 26-33% linear alkylbenzene sulfonate, about 4.5-6% isooctylphenyl polyethoxyethanol, about 0.25-3% polyoxyethylene sorbitan monooleate, about 4.5-6% lauric diethanolamide, about 0.25-2% monoethanolamide superamides, and water.
The invention also contemplates a method of formulating a Class D liquid firefighting agent, and a method of extinguishing a combustible metal fire applying the liquid firefighting agent described above with conventional firefighting liquid application apparatus.
It is the primary object of the present invention to provide an effective Class D firefighting liquid composition, and method of formulation and fire extinguishment utilizing the same, that is readily applied by conventional firefighting equipment. This and other objects of the invention will become clear from the detailed description, and the appended claims.